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NCT Number: NCT07244575

Association Between Preoperative Metformin Exposure and Postoperative Nausea and Vomiting in Patients Undergoing General Anesthesia

The aim of this observational study is to investigate the potential effects of metformin on postoperative nausea and vomiting (PONV) in patients undergoing surgery under general anesthesia. The primary research question is:

Does preoperative metformin exposure influence the incidence or severity of PONV in patients undergoing general anesthesia? Patients who are already prescribed metformin as part of their routine medical management will be compared with those not taking metformin. Data on PONV occurrence, severity, and recovery outcomes will be collected through structured postoperative surveys administered after surgery.

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Key information

Conditions

Postoperative Nausea and Vomiting Nausea Pathologic Processes Pathological Conditions, Signs and Symptoms Postoperative Complications Signs and Symptoms Signs and Symptoms, Digestive Vomiting

Age range

18 year and older

Sex eligibility

All sexes

Study type

Observational

Primary location

The Sixth Affiliated Hospital, Sun Yat-sen University

Guangzhou, Guangdong, 510655, China

Location status: Recruiting

Location contact

Yang Zhao, Doctor

CONTACT

[email protected]

0086-13802435520

About this study

This is a prospective observational cohort study involving patients undergoing surgery under general anesthesia with endotracheal intubation at the Sixth Affiliated Hospital of Sun Yat-sen University. A total of 909 participants will be enrolled into either the metformin-exposed group (n=303) or the non-exposed group (n=606) . The primary outcome is the incidence of postoperative nausea and vomiting (PONV) within 0-120 hours after surgery. Secondary outcomes comprise the incidence and severity of PONV during different intervals, use of antiemetics, and quality of recovery (assessed by the QoR-15 score).

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Voluntarily sign the informed consent form;
  • Age ≥ 18 years;
  • Patients who require surgical treatment under endotracheal intubation with general anesthesia as determined by the treating physician.

Exclusion criteria

  • Emergency surgery;
  • Currently taking medications with established antiemetic effects (e.g., corticosteroids, antipsychotics) due to underlying medical conditions;
  • Cognitive impairment or psychiatric disorders that preclude cooperation with questionnaire assessments;
  • Anticipated inability to extubate the tracheal tube postoperatively, which would interfere with outcome assessment;
  • Presence of nausea and/or vomiting prior to surgery.

Treatment and study plan

Primary outcomes

  1. The incidence of PONV during 0-120 postoperative hours

    Time frame: During 0-120 hour after surgery

    PONV is defined as the occurrence of any of the following symptoms: nausea, retching, or vomiting

Secondary outcomes

  1. The incidence PONV during 0-24 hour after surgery

    Time frame: During 0-24 hour after surgery

    PONV is defined as the occurrence of any of the following symptoms: nausea, retching, or vomiting

  2. The incidence PONV during 24-120 hour after surgery

    Time frame: During 24-120 hour after surgery

    Trained blinded investigators collected information about PONV recorded by either the participants and their family members or medical staff in the ward every 24 h during the first 120 h after surgery.

  3. The total severity of PONV during 0-120 hour after surgery

    Time frame: During 0-120 hour after surgery

    Assessment was performed using a simplified Postoperative Nausea and Vomiting (PONV) Impact Scale. Nausea severity was scored as follows: 0 (none), 1 (occasional), 2 (frequent), and 3 (continuous). Vomiting or retching was scored based on the number of episodes: 0, 1, 2, or 3 (or ≥3 episodes). The scores for nausea and vomiting/retching were summed to generate a total daily score for each 24-hour postoperative period. A total daily score of ≥5 was defined as clinically significant PONV. The overall PONV severity from 0 to 120 hours postoperatively was calculated as the sum of the daily scores over this period, providing a cumulative measure of symptom burden.

  4. The severity of PONV during 0-24 hour after surgery

    Time frame: During 0-24 hour after surgery

    Assessment was performed using a simplified Postoperative Nausea and Vomiting (PONV) Impact Scale. Nausea severity was scored as follows: 0 (none), 1 (occasional), 2 (frequent), and 3 (continuous). Vomiting or retching was scored based on the number of episodes: 0, 1, 2, or 3 (or ≥3 episodes). The scores for nausea and vomiting/retching were summed to generate a total daily score for each 24-hour postoperative period. A total daily score of ≥5 was defined as clinically significant PONV.

  5. The severity of PONV during 24-120 hour after surgery

    Time frame: During 24-120 hour after surgery

    Assessment was performed using a simplified Postoperative Nausea and Vomiting (PONV) Impact Scale. Nausea severity was scored as follows: 0 (none), 1 (occasional), 2 (frequent), and 3 (continuous). Vomiting or retching was scored based on the number of episodes: 0, 1, 2, or 3 (or ≥3 episodes). The scores for nausea and vomiting/retching were summed to generate a total daily score for each 24-hour postoperative period. A total daily score of ≥5 was defined as clinically significant PONV. The overall PONV severity from 25 to 120 hours postoperatively was calculated as the sum of the daily scores over this period.

  6. Use of antiemetics during 0-24 hours after surgery

    Time frame: During 0-24 hours after surgery

    Use of antiemetics after surgery

  7. Use of antiemetics during 24-120 hours after surgery

    Time frame: During 24-120 hours after surgery

    Use of antiemetics after surgery

  8. Use of antiemetics during 0-120 hours after surgery

    Time frame: During 0-120 hours after surgery

    Use of antiemetics after surgery

  9. Quality of Recovery (QoR-15 score) from 0 to 120 hour after surgery

    Time frame: Evaluated before surgery, at 24-hour, 48-hour, 72-hour, 96-hour, 120-hour after surgery

    The QoR-15 is a 15-item questionnaire instrument designed to evaluate the quality of postoperative recovery in patients. It comprises five sub-scales: pain (2 items), physical comfort (5 items), physical independence (2 items), psychological support (2 items), and emotional state (4 items). Each item is scored from 0 to 10, resulting in a total score ranging from 0 to 150. A higher score indicates a better quality of recovery for the patient.

Other outcomes

  1. Quality of recovery at 30-day after surgery

    Time frame: At 30-day after surgery

    The QoR-15 is a 15-item questionnaire instrument designed to evaluate the quality of postoperative recovery in patients. It comprises five sub-scales: pain (2 items), physical comfort (5 items), physical independence (2 items), psychological support (2 items), and emotional state (4 items). Each item is scored from 0 to 10, resulting in a total score ranging from 0 to 150. A higher score indicates a better quality of recovery for the patient.

  2. Incidence and grade of major postoperative complications

    Time frame: During 30 day after surgery

    Incidence and grade of major postoperative complications

  3. PONV-related factors in the blood or urine.

    Time frame: from preoperative to postoperative

    PONV-related factors in the blood or urine

  4. Overall survival rates

    Time frame: 1-year, 3-year, 5-year after surgery

    The status of live or death, and the death time

  5. Disease-free survival rates at 1-year, 3-year and 5-year, assessed exclusively among patients with cancer.

    Time frame: 1-year, 3-year and 5-year after surgery

    Disease-free survival rates

Study contacts

Contact information is provided by the study sponsor or research team.

Yang Zhao, Doctor

CONTACT

[email protected]

0086-02038254070

Sponsors and collaborators

Lead sponsor

Sixth Affiliated Hospital, Sun Yat-sen University

Other

Registry information

Official study title

Association Between Preoperative Metformin Exposure and Postoperative Nausea and Vomiting in Patients Undergoing General Anesthesia: a Prospective Observational Cohort Study

Acronym: Met-PONV

Important dates

Study start
2025
Primary completion
2028
Study completion
2033
First posted
Nov 24, 2025
Registry last updated
Feb 9, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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